Values for calculating RSI for 30-day length of stay
A hash (see package "hash"), where key is icd9cm code, and value is beta. Special key "popbeta" has the population beta for the entire table.
1. Sessler DI, Sigl JC, Manberg PJ, Kelley SD, Schubert A, Chamoun NG. Broadly applicable risk stratification system for predicting duration of hospitalization and mortality. Anesthesiology. 2010 Nov;113(5):1026-37. doi: 10.1097/ALN.0b013e3181f79a8d. http://my.clevelandclinic.org/anesthesiology/outcomes-research/risk-stratification-index.aspx